As reduction in size and thickness of electronic devices has advanced recently, there is increased need to connect minute circuits with one another, and to connect minute parts and minute circuits, etc. For example, there is a method in which an anisotropic electroconductive elastomer sheet is introduced between electronic parts and printed wiring boards to realize conduction.
Anisotropic electroconductive elastomer sheets are sheets of elastomer having electroconductivity only in a particular direction, and ensure electroconductivity only in the direction intended from the anisotropy thereof. Elastomer sheets generally include those with electroconductivity only in the thickness direction, those which exhibit electroconductivity in the thickness direction when pressure is applied in the thickness direction.
Conventionally, such anisotropic electroconductive elastomer sheets are formed by first forming an anisotropic electroconductive block by integrating arrayed metal fine wires with an insulator such as rubber or the like, and then finely cutting in the direction orthogonal to the direction in which the fine metal wires extend (e.g., Patent Document 1).
Also, as for a method for connecting signal lines of printed wiring boards disposed away from each other with a flexible connecting member, a method using flexible printed wiring boards is known. For example, connecting rigid printed wiring boards with a flexible printed wiring board enables signal lines between the rigid printed boards to be connected while keeping the signal transmission path flexible. With this method, rigid printed wiring boards are formed in multiple layers to reduce the size of the printed wiring boards and to realize increased installation density of electronic circuits, so multi-layer flexible printed boards are also used for the flexible printed wiring boards serving as the connecting member.
Patent Document 1 Japanese Unexamined Patent Application, First Publication No. 2000-340037